This project has now been completed. Twenty-three patients were enrolled at the University of Utah, with a total of 240 patients participating at twelve other sites across the nation. Although part of a multicenter trial, a specific hypothesis was tested by investigators at the University of Utah. Dr. Cannon doubted that immune complex absorption represented the mechanism by which protein A absorption exerted its therapeutic effect. An alternate hypothesis was proposed, stating that patients treated with protein A-perfused plasma developed immune responses to staphylococcal proteins leached from the column, which then altered immune responses to rheumatoid arthritis. The putative staphylococcal proteins were predicted to function as super antigens. Testing of the counter hypothesis was deemed an appropriate indication to make this a category A study by the GCRC Advisory Committee. The study has now been completed, and a preliminary analysis supports the hypothesis. A publication will be prepared describing the findings within the next year.